Osteoid osteoma of the hallux: a case report
The present case has been reported in the South African Orthopaedic Journa. Osteoid osteoma (OO) of the phalanges of the foot is a rare occurrence, making it a diagnostic dilemma. Classically OO presents with localised pain, which is worse at night.

An 8-year-old girl presented with a one-year history of left hallux pain. The GP diagnosed her with an ingrown toenail and managed it accordingly. Her symptoms did not resolve and thus the parents sought a second opinion. With regards to the history of her symptoms, the parents first noticed that her left hallux was larger than the right. She then started experiencing intermittent pain, which became progressively more frequent. The pain was worse after her ballet lessons.

She would use non-steroidal anti-inflammatory drugs (NSAIDs) on occasion, which helped significantly with the pain. On clinical examination she had a normal gait. The left hallux was significantly larger than the right. The skin was erythematous, with no increased local temperature. There was mild tenderness on deep palpation. Range of motion in the metatarsal phalangeal (MP) and interphalangeal (IP) joints was normal with no pain. The foot was neurovascularly intact. X-rays of the left hallux revealed a small oval lytic lesion in the distal phalanx with a central nidus.

CT scan of the left foot demonstrated soft tissue hypertrophy around the left hallux. There was a benign-looking rounded radiolucent lesion with a central calcified nidus measuring 4 mm in the proximal aspect of the diaphysis of the distal phalanx of the hallux. Surrounding bony sclerosis was present. An excisional biopsy of the lesion was done. The tumour was approached through a dorsolateral incision.

Her symptoms resolved dramatically post-operatively. Histology reported the presence of irregular bone trabeculae, showing a haphazard orientation. Evidence of osteoid formation was noted. There was associated osteoblastic rimming. The diagnosis of OO was confirmed.

At 6 weeks follow-up she had no symptoms and had resumed ballet. X-rays were repeated at 12 weeks post-surgery, which revealed no central nidus. She was contacted nine years after surgery for review. She reported no recurrence of the symptoms in the left hallux. Currently she performs modern dancing with no discomfort.

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